The necessity of bleaching or whitening teeth arises in many instances, for example, where teeth have undergone root canal therapy and have thus become darkened, when the teeth have been traumatized by an accident, or when a gradual discoloring of the teeth has occurred due either to aging or to staining caused by certain foods such as coffee or beets. Teeth may be bleached even where the patient simply desires whiter looking teeth for aesthetic purposes.
It is known from the prior art to deliver a peroxide bleaching solution, such as a solution known in the dental trade as "superoxol," to the surface of teeth for bleaching the same. Superoxol is a peroxide solution and is additionally necessarily activated by the application of heat. The prior art discloses the activation of superoxol by applying heat to the very surface of the patient's teeth. For example, according to a known method of the prior art, a concentrated solution of peroxide is applied to the tooth surface, and, thereafter, a beam of optical energy is focused onto the tooth structure in order to additionally activate the peroxide.
In U.S. Pat. No. 4,952,143 to Becker et al., a dental bleaching instrument is disclosed where a peroxide solution is applied to either an individual tooth or multiple teeth and, in order to achieve the desired bleaching effect, heat is applied directly to the bleaching solution present on the teeth.
French Publication No. 2 645 734 to Ardiot et al pertains to a dental treatment unit for whitening teeth with a liquid agent such as hydrogen peroxide. The unit consists of a pump, a molded mouthpiece which covers the gums and palate while leaving a space exposing the teeth to be treated, a temperature sensor and a UV radiation source. The mouthpiece has a jet directing the liquid agent to the teeth. The UV radiation source accelerates the bleaching process by directing UV rays to the mouthpiece in order to activate the liquid agent present therein.
In U.S. Pat. No. 4,983,381 to Zaragoza, a thermocube or thermo-containing plate including a thermic heating unit is placed in a capsule or circular surface thereof. The thermocube or thermo-containing plate cover the teeth and are thereafter heated to activate a whitening agent for whitening the teeth. Here again, temperature is applied directly to the teeth.
U.S. Pat. No. 4,793,807 to Friedman et al concerns a delivery system for delivering a liquid heated to a predetermined temperature to the oral cavity of a patient. The liquid in question is not a bleaching agent, but a chemical solution which softens dental caries and thus aids in their removal.
The bleaching methods and apparatuses of the prior art have the disadvantage of yielding peroxide molecules which are not released until after the liquid bleaching solution has been delivered to the surface of the teeth. Because of the above, the bleaching capacity of the peroxide molecules is decreased, since the molecules have to overcome the surface tension of the bleaching solution liquid present on the surface of a tooth to be bleached in order to reach that surface and bleach the same.
In addition, the prior art necessarily requires the application of heat, sometimes using ultraviolet rays, directly to the oral cavity of the patient. With regard to the above, the prior art is limited, in the sense that any variation in the temperature of the bleaching solution, or any monitoring and/or regulation of that temperature, necessarily occurs directly on the surface of the tooth to be bleached. Thus, the prior art does not allow a monitoring/regulation of the temperature of the bleaching molecules for optimum bleaching before the peroxide reaches the tooth surface. Moreover, it is widely known, as shown by numerous studies, that ultraviolet rays have a negative effect upon both dentists and dental technicians working proximal to such rays, and the patient whose teeth are being treated. It is not clear whether the long term effects of exposure to ultraviolet rays have been fully appreciated.
To the extent that the prior art involves activation of a bleaching solution directly on the surface of a tooth to be bleached, it furthermore does not permit the delivery of a bleaching vapor in the form of a pressurized jet or stream to the tooth to be bleached. Since the use of a pressurized jet or stream increases the bleaching capacity of the vapor by allowing the same to more easily enter the enamel tubules, the prior art disadvantageously involves a bleaching process which is relatively slow and painstaking for both the patient and the dental practitioner.
It is an object of the invention to provide a method and apparatus for bleaching teeth where a bleaching vapor containing concentrated oxygen is delivered to the surface of a tooth to be bleached. According to the above object, the peroxide molecules may readily enter the enamel tubules of the tooth for bleaching the same without having to overcome the surface tension of a bleaching solution present on the tooth surface.
It is yet another object of the invention to provide a method and apparatus for bleaching teeth of the above type where a temperature of the bleaching vapor can be regulated before the vapor reaches the surface of the tooth to be bleached for maintaining an optimum temperature range of the bleaching vapor.
It is a further object of the invention to provide a method and apparatus for bleaching teeth where the use of ultraviolet rays is obviated.
It is yet a further object of the invention to provide a method and apparatus for bleaching teeth where the bleaching vapor can be delivered to the surface of the tooth to be bleached in the form of a pressurized jet or stream of bleaching vapor.